How to Use an Onsen in Japan: A First-Timer's Guide
A few years ago, I fell in love with onsen. Once it clicked, it really clicked — and this month, I took that passion a step further and became a certified Onsen Sommelier.
When I started Japan with Takuma, writing a guide like this felt like the natural first step. Onsen is one of the best experiences Japan has to offer, and I want every visitor to actually enjoy it — not feel anxious about the rules or walk away unsure if they did it right.
This guide covers how to use an onsen properly, based on what I've learned both from years of soaking and from my Onsen Sommelier training.
What is an onsen?
An onsen is a natural hot spring. To be officially classified as one under Japanese law, the water must emerge from the ground at 25°C or above, or contain a specific concentration of minerals.
That mineral content is what makes onsen feel different from a regular bath. Depending on the type of spring, the water can feel silky, slightly sulfuric, or faintly metallic. Some types are said to help with fatigue, skin conditions, or joint pain — and whether or not you believe the health claims, the effect on your body is real.
Onsen is not the same as a sento, which is a public bathhouse that uses regular heated water. If you want the real thing, check that the facility is using actual spring water.
Before you get in
Most first-timers walk straight to the bath. That's the wrong order.
Drink water before you enter
Soaking in hot water causes your body to sweat, which thickens the blood. Drinking a glass of water before you get in — and again after you get out — helps your circulation stay comfortable throughout. This is something most guides skip, but it makes a noticeable difference, especially on your first visit.
Wash at the shower station
Every onsen has a row of shower stations before the baths. This isn't optional — you wash your entire body here before entering the shared water. Sit on the stool provided, use the soap and shampoo available, and rinse thoroughly. No soap should go into the bath.
Do the kakeyu (pre-rinse) properly
Kakeyu means pouring water over yourself before entering the bath. Most people treat it as a quick splash and move on. It's actually more important than that.
The correct way is to start from your feet and work upward toward your heart. This gradually acclimates your body to the temperature and reduces the shock on your cardiovascular system. It also rinses off any remaining soap. Take your time with it — thirty seconds done properly is better than a rushed pour.
The Onsen Sommelier's Five Bathing Principles
This is the part most guides don't cover. Getting into the water is easy. Getting the most out of it takes a little more intention.
1. Hydrate before and after
Already mentioned above, but worth repeating because it's that important. Onsen dehydrates you more than you'd expect. Keep water close by, especially if you're planning multiple soaks.
2. Kakeyu from feet upward
Same principle. Don't skip this between soaks either — if you've stepped outside to cool down and are re-entering the bath, do it again.
3. Put a wet towel on your head
You'll see Japanese bathers doing this and wonder why. When you're submerged in hot water, blood flow increases throughout your body, but the blood supply to your head actually decreases. A cool, wet towel helps keep the blood vessels in your head from overheating — reducing the chance of dizziness or feeling faint.
One note from my Sommelier training: use a cold towel for indoor baths and outdoor baths in summer. For outdoor baths in winter, a warm towel is better — a cold towel in cold air can cause the blood vessels in your head to contract too quickly.
4. Soak in short intervals — split bathing
Rather than staying in for one long session, get in for a few minutes, get out and rest, then get back in. Repeat two or three times.
A three-minute soak followed by rest, repeated three times, gives you nine minutes of total immersion — and your body retains the heat much better than a single ten-minute session would. It's also easier on your heart.
5. Alternate hot and cold water on your knees for fatigue recovery
If you're tired from a long day of walking — which is likely if you're visiting as a tourist — try alternating warm and cold water on your knees: about three minutes warm, one minute cold, repeated three to five times.
This stimulates the peripheral blood vessels, which helps flush out lactic acid and speeds up recovery. The effect is noticeably different from a regular soak. Use the shower station for this rather than the main bath.
A few things to know before you go
You bathe fully nude. Swimsuits are not permitted in most onsen. This is the part that makes many first-timers nervous, and I completely understand that. But once you're inside, you'll notice quickly that nobody is paying attention to you. The atmosphere is quiet and inward-focused. It becomes normal within about two minutes.
Your phone stays in the locker. Photography is prohibited in all onsen bathing areas. Leave your phone in the changing room — this is strictly observed.
It will be hotter than you expect. Japanese onsen typically sit between 40–44°C. If you're not used to it, start with a shorter soak and work up gradually. There's no shame in sitting on the edge and just letting your feet soak while you adjust.
Move slowly and keep quiet. The mood of an onsen is calm and unhurried. Loud conversations, splashing, or rushing around disrupts that for everyone. Treat it like a library, not a swimming pool.
Thinking about trying onsen on your trip?
Kanagawa — the region just south of Tokyo — has some excellent onsen options, from large modern facilities to traditional ryokan with private baths. It's one of my favorite things to include in a day trip itinerary for visitors staying in Tokyo.
If you'd like recommendations tailored to your trip — including where to find onsen that suits your pace, travel style, and who you're traveling with — I make personalized Kanagawa day trip itineraries for ¥5,000, delivered as a PDF within 7 days. Request yours here →
Quick tips
- Bring a small towel (or rent one at the facility — usually ¥100–300)
- Drink water before entering, and again after
- Remove all jewelry before soaking
- Tie up long hair so it doesn't touch the water
- Don't drink alcohol before an onsen
- If you feel dizzy, get out slowly and sit down before standing fully upright